Various products require a coating applied thereto to be baked to cure the coating so that it is fixed to the part. One example is that of circuit boards where a coating is applied and then baked. Another example relates to the powder coating of metal parts which is a relatively recent method for protecting and beautifying products. Powder coating makes a product highly chip and scratch resistant and a highly chemical, petroleum and salt resistant. Powder coating has the ability to apply a thick, even coat without drips or sags and has premium insulating qualities, both electrical and thermal and also removes the cold feeling from metals. It gives a decorative finish to a product along with a protective finish which is resistant to fading. Powder coating has the ability to encapsulate products, wrap around corners, help eliminate sharp edges achieve with one high quality coat with no primary necessary and can resist abuse in low and high temperature variances. Powder coating has virtually unlimited number of colours and a wide variety of finishes.
Generally powder coating is applied to many metal products powder coatings are 100% solids coatings applied as a dry powder mix of resin and pigment and subsequently formed into a film with heat. The solid resin binder melts upon heating, binds the pigment, and results in a pigment coating upon cooling. The powder is applied either by an electrostatic spray or by passing the part over a fluidised bed of powder. In both cases the parts undergo subsequent oven heating to provide a smooth continuous film.
Powder coated materials have to be heated in an oven or the like, an example of a powder coat oven is shown in U.S. Pat. No. 5,155,335 of Habaki et al wherein the oven has an inlet air shield chamber connected to a horizontal heating chamber. The oven of Habaki has a generally horizontal conveyor which is limited to one item at a time in the oven on the conveyor which is adequate for large items which need to be relatively spaced out but is not very effective for small items such as jewellery and the like.
U.S. Pat. No. 4,009,301 of Heckman et al discloses a method for powder coating materials. A large apparatus is used to carry items on a conveyor through a series of steps wherein the item is powder coated and baked.
U.S. Pat. No. 5,000,985 of Salisbury shows a similar method of powder coating wherein materials are carried on a conveyor through the processes.
The above patents are not effective for small objects and are relatively inefficient. it will be appreciated that the parts which are relatively small are generally suspended on the carriage from a hook or the like so that each is separate as it passes through the oven.